JPS603678A - Developing device of magnetic copying machine - Google Patents

Abstract

PURPOSE:To obstruct a toner cloud, and to prevent the generation of contamination, etc. of a device by providing a means for making air flow into, from the outside, the inside of a developing housing in which a magnetic toner is contained, and preventing the leakage of the toner. CONSTITUTION:A developing housing 4 is constituted of an inside housing 4a and an outside housing 4b; and an air inflow port 9 and an air outflow port 14 are provided on the outside housing 4b and the inside housing 4a, respectively. Air of a compressor, etc., which is led from an air feed pipe 10 passes through an air inflow path 11, flows into the inside housing 4a from the first inlet side opening 12 and he first outlet side opening 13, and it is exhausted from an outflow path 14. Therefore, the leakage of a toner from the openings 12, 13 is prevented, the generation of a toner cloud is obstructed, and the generation of contamination of an apparatus in a device is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device for a magnetic copying machine using magnetic toner.

A conventional magnetic copying machine forms a magnetic latent image on a magnetic recording medium that can be magnetized, and transfers it to magnetic toner (for example, sensitive colored particles containing fine magnetic particles in a polymer resin, which are sensitive to the force of a magnetic field). A permanent image is created by developing the image by electrostatically or magnetically transferring it to paper, etc., and fixing it by heat, pressure, etc. After transfer, either the residual magnetic toner is removed and the image is transferred to the next development cycle, or the magnetic latent image is demagnetized, a new magnetic latent image is formed, and the process is repeated again. returned.

Various methods can be considered as developing methods for such magnetic copying machines. Particularly in the case of powder marking methods that use magnetic toner, a simple method, such as the one-component magnetic toner development method used in electrophotography, uses a magnetic brush to transport the magnetic toner and bring it into contact with the magnetic latent image. It is possible to provide a developing device.

However, in the electrophotographic method that forms an electrostatic latent image, a magnetic brush that generates a relatively large magnetic flux density can be used to transport the magnetic toner and prevent the toner from separating from the magnetic brush. In the case of a copying machine, in order to avoid demagnetizing the magnetic latent image, it is necessary to weaken the magnetic flux to a level that does not exceed the coercive force of the magnetic material that holds the magnetic latent image, at least in the part closest to the magnetic latent image. .

However, in the magnetic brush developing device of a conventional magnetic copying machine, like the magnetic brush developing device W of an electrophotographic copying machine, the side where the magnetic latent image comes out from the developing housing is designed to prevent toner from leaking from the developing housing. That is, except for the exit side of the developer housing, a sealing member such as a sponge or blade that makes mechanical contact is used in the area adjacent to the magnetic latent image carrier.However, this sealing member alone can prevent 11. ! The disadvantage is that leakage from the image housing cannot be prevented, creating a toner cloud that contaminates other equipment in the copier, such as magnetic heads or heating heads for magnetic image formats. In particular, the occurrence of such toner clouds was particularly noticeable during high-speed copying on the exit side of the developer housing where no mechanical contact sealing member could be provided in order to prevent the developed image from leaking out.

OBJECTS OF THE INVENTION The present invention provides a developing device for a magnetic copying machine that has a simple structure and prevents leakage of toner from a developing housing song, eliminating drawbacks in the prior art such as contamination of other devices in the copying machine. It is.

Structure of the Invention The present invention is characterized in that, in a developing device for a magnetic copying machine, means is provided for causing air to flow from the outside into the inside of the developing housing where magnetic toner exists, thereby preventing leakage of toner from the developing housing. shall be.

The air inlet means is provided by separating the developer housing into an inner housing in which magnetic toner is present and an outer housing, and by providing an air inlet in the outer housing and an air outlet in the inner housing, or by providing an air suction port in the developer housing. This is achieved by providing

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a cylindrical magnetic latent image carrier, 2 is a magnetic head, 3 is a degaussing head, and 4 is a developing housing. The developing housing 4 consists of an inner housing 4a and an outer housing 4b, and a cylinder 6 having a built-in magnet roll 5 is provided inside the inner housing 4a. The cylinder 6 and the magnetic latent image carrier 1 are driven in the directions of arrows a and b, respectively. In FIG. 7, the cylinder 6 is rotated in the opposite direction to the rotation direction of the magnetic latent image carrier 1, but it may be rotated in the same direction. Magnetic toner 7 is present within the inner housing 4a;
It is attracted to the cylinder surface by the magnetic force of the magnet roll 5 and is transported to the developing area as the cylinder rotates. At this time, the magnetic toner 7 is regulated to a predetermined toner thickness by a layer thickness regulating member 8 provided on the inner wall of the internal housing 4a.

The outer housing 4b is provided with an air inlet 9, and an air supply pipe 10 connected to an air compression device such as a compressor or a blower fan (not shown) is attached to the air inlet 9. An air flow path 11 is provided between the inner housing 4a and the outer housing 4b, and air passes through the air flow path 11 to form a gap between the inner housing 4a and the surface of the magnetic latent image carrier 1. It flows into the internal housing 4a from the first entrance opening 12 and the first exit opening 13. The inner housing 4a is provided with an air outlet passage 14,
This air outflow path 14 is connected to a filter, a separation device, etc. (not shown) that separates magnetic toner from air.

A first output side groove 13 and an a-th output side groove 15 are provided between the external housing 4b and the surface of the magnetic latent image carrier 1. The second entrance opening opening 14 and the a-th exit opening opening 15 are the same as the first entrance opening opening 12 and the first exit opening opening 13.
Compared to this, the width of the gap is smaller and the length is longer. Therefore, the former has greater resistance to airflow than the latter. Therefore, the air that has passed through the air flow path 11 reliably flows into the internal housing 4a as shown by the bold line arrow in the figure, thereby causing the magnetic toner to enter the first inlet side port 12 and the first outlet side open port. 13 can be prevented from leaking. Further, although not shown, a mechanically contacting sealing member such as a sponge or a blade may be used for the second input port 15. However, there is a possibility that the developed image may be disturbed in the second exit side opening 16, so it is preferable to provide a sealing means using air flow as described above. A method for increasing the sealing effect is to appropriately select the width and length of the gap of the first opening 12° 13 compared to the λ-th opening 15° 16, thereby reducing the air flow resistance in the former in the latter. It is also possible to reduce air flow resistance.

Furthermore, on the entrance side where the magnetic latent image enters the developing housing 4, as the magnetic latent image carrier 1 moves, air from the outside flows into the housing 4 through the No. However, on the exit side where the magnetic latent image exits the developing housing 4, the magnetic latent image carrier 1
With the movement of the housing 4, there is a possibility that the internal air may flow out of the housing 4 through the λ-th outlet opening 16. Therefore, on the exit side, it is necessary to add a large air flow to the air flow accompanying the movement of the magnetic latent image carrier 1.

FIG. 2 shows another example of the magnetic brush developing device of the present invention, in which the developing housing 17 does not have a 92-layer structure unlike that in FIG. A cylinder 19 containing a magnet roll 18 is disposed within the developing roller 1, and the cylinder 19 and the magnetic latent image carrier 1 rotate in the same direction as shown by arrows a and b, respectively. The magnetic toner 20 deposited on the bottom of the developing housing 17 is supplied to the surface of the cylinder 19 by a toner supplying member 21 and transported to the developing area O while being regulated by a toner thickness regulating member 22 .

An entrance port 23 and an exit port 24 are provided on the side of the developer housing 1T adjacent to the magnetic latent image carrier 1. Both the entrance side opening 23 and the exit side opening 24 have a gap having a small width and a long length, and have a large resistance to the air flow. Developing housing 1
7 is further provided with an air flow inlet 25, which is connected to a pressure reducing device (not shown) such as a fan or a vacuum pumper.

A magnetic toner collection mechanism is provided adjacent to the airflow inlet 25, and this magnetic toner collection mechanism comes into contact with a collection magnet roll 26, a rotating cylinder 27, a cylinder such as a blade or mylar, etc. It is composed of a seal member 28. The magnetic toner collection mechanism allows magnetic toner to be separated from the magnetic toner cloud generated within the developer housing by the vacuum applied to the airflow inlet 25.

In the embodiment shown in Figure 1, the pressure inside the developer housing is reduced! Therefore, air flows in from the outside through the inlet side opening 23 and the outlet side opening 24, and this airflow prevents toner from leaking to the outside.

In this embodiment as well, the exit side listening port 2 is similar to the embodiment shown in FIG.
4, an air flow is considered to move together with the magnetic latent image carrier 1, so it is preferable to adjust the reduced pressure so that the air flow from the outside to the inside becomes larger.

Although the embodiments described above all show examples in which the present invention is applied to a magnetic brush developing device, the present invention can also be applied to other developing devices such as a cascade.

Effects of the Invention According to the present invention, since a means for flowing air from the outside into the inside of the developer housing where magnetic toner is present is provided, it is possible to prevent leakage of toner from the developer housing, and therefore toner cloud is prevented. can be prevented from occurring.

Furthermore, it is possible to improve the conventional drawbacks such as fogging in non-image areas caused by the magnetic toner image after development being exposed to a toner cloud, especially on the exit side.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of the magnetic brush developing device of the present invention, and FIG. 1 is a schematic cross-sectional view showing a fourth embodiment of the magnetic brush developing device of the present invention. 1... Magnetic latent image carrier, 2... Magnetic head, 3...
・Degaussing head, 4.17...Development housing, 4a・
...Inner housing, 4b...Outer housing, 5.
18°25... Magnet roll, 6, 19.26... Cylinder, 8.22... Toner thickness regulating member, 9...
Air inlet, 12... First inlet side opening, 13... First outlet side opening, 14... Air outlet, 15... Second
Inlet side opening, 16... λth outlet side opening, 21... Toner supply member, 23... Inlet side opening, 24... Outlet side opening, 25... Air blowing port, 26... Collection magnet roll, 27... Rotating cylinder, 28... Seal member.

Claims (1)

[Claims] A developing device for a magnetic copying machine, characterized in that means is provided for causing air to flow from the outside into a developing housing where magnetic toner exists, thereby preventing leakage of toner from the developing housing.